Assessment of in vitro Multiplication of Lemna minor in the Presence of Phenol: Plant/Bacteria System for Potential Bioremediation - Part I

The aim of this work was to examine the multiplication of the common duckweed (Lemna minor), an aquatic plant species widespread in European stagnant waters, in two different media (Murashige - Skoog and Hoagland) with and without phenol supplementation. In order to quantify plant multiplication we have used relative growth rate and tolerance indices on both tested media and at five phenol concentrations (10, 15, 20, 30 and 100 mg/L). Furthermore, we examined the possibility of phenol removal from aqueous media containing different phenol concentrations, by using plant/bacteria system consisting of the duckweed and its naturally occurring microbial populations. After 7 days, number of newly formed fronds was approximately four times higher than at the beginning of the experiment on both tested media. The most important result in this study was removal of 70% of phenol from the highest initial concentration of 100 mg/L, in mixed cultures of duckweed and bacteria. By comparison, aseptic duckweed cultures removed approximately 50% of phenol at the same initial concentration. Our duckweed specimen showed a fast reproduction rate, high tolerance to phenol and a possible cooperation with rhizosphere-associated bacteria. All of these traits can be ultimately utilized for bioremediation purposes.